Suppose that a researcher wished to learn if a certain
drug slows the growth of tumors. She obtained mice with tumors and randomly
divided them into two groups. She then injected one group of mice with the
drug and used the second group as a control. After 2 weeks, she sacrificed
the mice and weighed the tumors. The mean weight of tumors for each group of
mice is below.
Drug group =
0.39 g
Control group = 0.42 g
She used a 1-tailed t-test. The probability (p) = 0.012.
What should she conclude? Why?
Suppose that a researcher wishes to learn whether the pH of soil affects
seed germination of a particular herb found in forests near her home. She
believes that acid soils (low pH) will have less germination. She filled 10
flower pots with acid soil (pH 5.5) and ten flower pots with neutral soil
(pH 7.0) and planted 100 seeds in each pot. The mean number of seeds that
germinated in each type of soil is below.
acid soil: 42.5 seeds germinated per pot
neutral soil: 51.1 seeds germinated per pot
She used a 1-tailed t-test. The probability (p) = 0.082.
What should she conclude? Why?
Suppose that a researcher wished to learn if a
particular chemical is toxic to a certain species of beetle. She believes
that the chemical might interfere with the beetle’s reproduction. She
obtained beetles and divided them into two groups. She then fed one group of
beetles with the chemical and used the second group as a control. After 2
weeks, she counted the number of eggs produced by each beetle in each group.
The mean egg count for each group of beetles is below.
Chemical group = 32.5 eggs
Control group = 43.1 eggs
She used a
1-tailed t-test. The probability (p) = 0.072.